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Re: How to enable soft-float support in newlib and gcc toolchains for an i386 target

Here is the procedure that I followed, you might be able to see a more clearer picture of my gcc toolchain build procedure.

1) Binutils
  ${TMP_DIR}/${BINUTILS_DIR}/configure  \
  --prefix=${INSTALL_DIR}               \
  --target=${TARGET}                    \
  --disable-nls                         \
  --disable-werror                      \
  --enable-multilib                     \
  --with-float=soft                     \
  --enable-soft-float                   \
    &> logs/configure.log || return

  make install

2) GCC Bootstrap
  ${TMP_DIR}/${GCC_DIR}/configure   \
  --prefix=${INSTALL_DIR}           \
  --target=${TARGET}                \
  --disable-nls                     \
  --enable-multilib                 \
  --with-newlib                     \
  --enable-soft-float               \
  --enable-interwork                \
  --enable-languages=c      &> logs/configure.log || return

  make all-gcc
  make install-gcc

3) Newlib
  ${TMP_DIR}/${NEWLIB_DIR}/configure      \
  --prefix=${INSTALL_DIR}                 \
  --target=${TARGET}                      \
  --disable-nls                           \
  --enable-multilib                       \
  --enable-interwork                      \
  --enable-newlib-io-long-long            \
  --enable-newlib-io-long-double          \
  --enable-newlib-io-c99-formats          \
  --disable-newlib-may-supply-syscalls    \
  --enable-newlib-multithread             \
  --with-float=soft                       \
  --enable-soft-float                     \
  --disable-newlib-supplied-syscalls      &> logs/configure.log || return

  make install

4) GCC Final
  make all
  make install

Here ${TARGET} is "i386-sls-dnaos" which is an i386 target with DNAOS ( support.

Key points:
- The gcc configure does not accept "--with-float=soft" option !!!
- When we talk about "soft-float" support, do I need to look into my target specific code i.e. i386 dnaos ? or its a generic multilibs issue?
- The gcc version of source code that I am using is "4.4.2" with binutils version "2.18" and newlib version "1.18.0"

Thanks for your support,

On 08/02/2011 03:53 PM, Joel Sherrill wrote:
On 08/02/2011 06:16 AM, Mian M. Hamayun wrote:
Hello Everyone,

I am newbie to newlib and gcc toolchains, so my question may be a
little ambiguous for this forum.

In fact I am trying to build a gcc toolchain with newlib for an i386
target which doesn't support hw float/mmx instructions. In fact it is
a virtual machine which I am targeting.
So when I compile my applications with "-msoft-float" flag, I get
quite a few unresolved symbols.

The support of the soft-float multilibs is dependent on the
target which the compiler was built for. And the gcc version.
Without that information, it is hard to answer.

For Example:
Sources/susan.c:979: undefined reference to `__floatsisf'
Sources/susan.c:979: undefined reference to `__divsf3'
Sources/susan.c:1626: undefined reference to `__subdf3'
Sources/susan.c:1628: undefined reference to `__mulsf3'

These are gcc support methods. So it is up to how gcc is built.
So my obvious 'guess' is to rebuild the gcc toolchain and/or newlib
using "--with-float=soft" and/or "--enable-soft-float" options. But so
far I haven't been able to build a toolchain that solves this issue.

Any help / pointers in this regard will be greatly appreciated.
Please also point-out if this is not the right forum for this type of

Best Regards,

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